title: Investigation of composite materials using SLM-based phase retrieval.
abstract: We present a robust method to inspect a typical composite material constructed of carbon fiber reinforced plastic (CFRP). It is based on optical surface contouring using the spatial light modulator (SLM)-based phase retrieval technique. The method utilizes multiple intensity observations of the wave field, diffracted by the investigated object, captured at different planes along the optical axis to recover the phase information across the object plane. The SLM-based system allows for the recording of the required consecutive intensity measurements in various propagation states across a common recording plane. This overcomes the mechanical shifting of a camera sensor required within the capturing process. In contrast to existing phase retrieval approaches, the measuring time is considerably reduced, since the switching time of the SLM is less than 50 ms. This enables nondestructive testing under thermal load. Experimental results are presented that demonstrate the approach can be used to assess structural properties of technical components made from CFRP.
authors.affiliation: BIAS-Bremer Institut für angewandte Strahltechnik, Klagenfurter Str.2, Bremen 28359, Germany. agour@bias.de
authors.forename: Mostafa
authors.initials: M
authors.lastname: Agour
authors.forename: Claas
authors.initials: C
authors.lastname: Falldorf
authors.forename: Ralf B
authors.initials: RB
authors.lastname: Bergmann